<?php
/**
 * Revision/log/file deletion backend
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup RevisionDelete
 */

/**
 * Temporary b/c interface, collection of static functions.
 * @ingroup SpecialPage
 * @ingroup RevisionDelete
 */
class RevisionDeleter {
	/**
	 * Checks for a change in the bitfield for a certain option and updates the
	 * provided array accordingly.
	 *
	 * @param string $desc description to add to the array if the option was
	 * enabled / disabled.
	 * @param $field Integer: the bitmask describing the single option.
	 * @param $diff Integer: the xor of the old and new bitfields.
	 * @param $new Integer: the new bitfield
	 * @param array $arr the array to update.
	 */
	protected static function checkItem( $desc, $field, $diff, $new, &$arr ) {
		if( $diff & $field ) {
			$arr[ ( $new & $field ) ? 0 : 1 ][] = $desc;
		}
	}

	/**
	 * Gets an array of message keys describing the changes made to the
	 * visibility of the revision.
	 *
	 * If the resulting array is $arr, then $arr[0] will contain an array of
	 * keys describing the items that were hidden, $arr[1] will contain
	 * an array of keys describing the items that were unhidden, and $arr[2]
	 * will contain an array with a single message key, which can be one of
	 * "revdelete-restricted", "revdelete-unrestricted" indicating (un)suppression
	 * or null to indicate nothing in particular.
	 * You can turn the keys in $arr[0] and $arr[1] into message keys by
	 * appending -hid and and -unhid to the keys respectively.
	 *
	 * @param $n Integer: the new bitfield.
	 * @param $o Integer: the old bitfield.
	 * @return array An array as described above.
	 * @since 1.19 public
	 */
	public static function getChanges( $n, $o ) {
		$diff = $n ^ $o;
		$ret = array( 0 => array(), 1 => array(), 2 => array() );
		// Build bitfield changes in language
		self::checkItem( 'revdelete-content',
			Revision::DELETED_TEXT, $diff, $n, $ret );
		self::checkItem( 'revdelete-summary',
			Revision::DELETED_COMMENT, $diff, $n, $ret );
		self::checkItem( 'revdelete-uname',
			Revision::DELETED_USER, $diff, $n, $ret );
		// Restriction application to sysops
		if( $diff & Revision::DELETED_RESTRICTED ) {
			if( $n & Revision::DELETED_RESTRICTED )
				$ret[2][] = 'revdelete-restricted';
			else
				$ret[2][] = 'revdelete-unrestricted';
		}
		return $ret;
	}

	/** Get DB field name for URL param...
	 * Future code for other things may also track
	 * other types of revision-specific changes.
	 * @return string One of log_id/rev_id/fa_id/ar_timestamp/oi_archive_name
	 */
	public static function getRelationType( $typeName ) {
		if ( isset( SpecialRevisionDelete::$deprecatedTypeMap[$typeName] ) ) {
			$typeName = SpecialRevisionDelete::$deprecatedTypeMap[$typeName];
		}
		if ( isset( SpecialRevisionDelete::$allowedTypes[$typeName] ) ) {
			$class = SpecialRevisionDelete::$allowedTypes[$typeName]['list-class'];
			return call_user_func( array( $class, 'getRelationType' ) );
		} else {
			return null;
		}
	}

	/**
	 * Checks if a revision still exists in the revision table.
	 * If it doesn't, returns the corresponding ar_timestamp field
	 * so that this key can be used instead.
	 *
	 * @param $title Title
	 * @param  $revid
	 * @return bool|mixed
	 */
	public static function checkRevisionExistence( $title, $revid ) {
		$dbr = wfGetDB( DB_SLAVE );
		$exists = $dbr->selectField( 'revision', '1',
				array( 'rev_id' => $revid ), __METHOD__ );

		if ( $exists ) {
			return true;
		}

		$timestamp = $dbr->selectField( 'archive', 'ar_timestamp',
				array( 'ar_namespace' => $title->getNamespace(),
					'ar_title' => $title->getDBkey(),
					'ar_rev_id' => $revid ), __METHOD__ );

		return $timestamp;
	}
}
